TiAlCN layers with lamellar structure

Abstract

A tool has a main part of hard metal, cermet, ceramic, steel, high-speed steel, and a single or multilayer wear protection coating applied onto the main part by CVD and which has a thickness from 3 μm to 25 μm. The wear protection coating has at least one Ti 1−x Al x C y N z layer with stoichiometric coefficients 0.70≤x<1.0≤y<0.25 and 0.75≤z<1.15 and a thickness from 1.5 μm to 17 μm. The T 1−x Al x C y N z layer has a lamellar structure with lamellae with thickness of no more than 150 nm, preferably no more than 100 nm, particularly preferably no more than 50 nm. Lamellae are made of periodically alternating regions of the Ti 1−x Al x C y N z layer with alternatingly different stoichiometric proportions of Ti and Al, having the same crystal structure (crystallographic phase), and the Ti 1−x Al x C y N z layer has at least 90% vol. % of face centered cubic (fcc) crystal structure.

The invention claimed is: 
     
       1. A tool comprising a base body of carbide, cermet, ceramic, steel or high speed steel, and a single-layer or multi-layer wear-protection coating applied thereto in a CVD process and of a thickness in the range of 3 μm to 25 μm,
 wherein the wear-protection coating has at least one Ti 1−x Al x C y N z  layer having stoichiometry coefficients 0.70<x<1, 0<y<0.25 and 0.75<z<1.15, and with a thickness in the range of 1.5 μm to 17 μm, 
 wherein the Ti 1−x Al x C y N z  layer has a lamellar structure with lamellae of a thickness of not more than 150 nm, 
 wherein the lamellae are formed from periodically alternating regions of the Ti 1−x Al x C y N z  layer with alternately different stoichiometric proportions of Ti and Al, having the same crystal structure (crystallographic phase), and 
 wherein the Ti 1−x Al x C y N z  layer has at least 90 vol-% of face-centred cubic (fcc) crystal structure. 
 
     
     
       2. A tool according to  claim 1 , wherein the Ti 1−x Al x C y N z  layer has at least 95 vol-% of face-centred cubic (fcc) crystal structure. 
     
     
       3. A tool according to  claim 1 , wherein in the Ti 1−x Al x C y N z  layer with lamellae comprising periodically alternating regions with alternately different stoichiometric proportions of Ti and Al regions with other Ti and Al proportions which respectively adjoin below and above a region of the lamellae in the layer growth direction have the same crystallographic orientation. 
     
     
       4. A tool according to  claim 1 , wherein the Ti 1−x Al x C y N z  layer has a columnar microstructure,
 wherein the columnar crystallites have a mean length which is at least 0.35 times the thickness of the Ti 1−x Al x C y N z  layer, and/or 
 wherein the columnar crystallites have a ratio of the mean length to the mean width, measured at 50% of the thickness of the Ti 1−x Al x C y N z  layer, of at least 2.5. 
 
     
     
       5. A tool according to  claim 4 , wherein the mean length of the columnar crystallites is at least 0.5 times the thickness of the Ti 1−x Al x C y N z  layer. 
     
     
       6. A tool according to  claim 4 , wherein the ratio of the mean length to the mean width of the columnar crystallites, measured at 50% of the thickness of the Ti 1−x Al x C y N z  layer, is at least 5. 
     
     
       7. A tool according to  claim 1 , wherein the Ti 1−x Al x C y N z  layer has a preferential orientation of crystal growth with respect to a crystallographic {hkl} plane, characterised by a texture coefficient TC (hkl)>1.5,
 wherein the texture coefficient TC (hkl) is defined as follows: 
 
       
         
           
             
               
                 
                   TC 
                   ⁡ 
                   
                     ( 
                     hkl 
                     ) 
                   
                 
                 = 
                 
                   
                     
                       
                         I 
                         ⁡ 
                         
                           ( 
                           hkl 
                           ) 
                         
                       
                       
                         
                           I 
                           0 
                         
                         ⁡ 
                         
                           ( 
                           hkl 
                           ) 
                         
                       
                     
                     ⁡ 
                     
                       [ 
                       
                         
                           1 
                           n 
                         
                         ⁢ 
                         
                           
                             ∑ 
                             
                               n 
                               = 
                               1 
                             
                             n 
                           
                           ⁢ 
                           
                               
                           
                           ⁢ 
                           
                             
                               I 
                               ⁡ 
                               
                                 ( 
                                 hkl 
                                 ) 
                               
                             
                             
                               
                                 I 
                                 0 
                               
                               ⁡ 
                               
                                 ( 
                                 hkl 
                                 ) 
                               
                             
                           
                         
                       
                       ] 
                     
                   
                   
                     - 
                     1 
                   
                 
               
               , 
             
           
         
         wherein 
         l(hkl) are the intensities of the diffraction reflexes, measured by X-ray diffraction, 
         lo(hkl) are the standard intensities of the diffraction reflexes in accordance with PDF chart 00-046-1200, 
         n is the number of reflexes used for the calculation, and 
         the reflexes (111), (200), (220) and (311) are used for the calculation of TC(hkl), and 
         wherein the preferential orientation of the crystal growth of the Ti 1−x Al x C y N z  layer is present with respect to the crystallographic {111}-, {200}-, {220}- or {311}-plane. 
       
     
     
       8. A tool according to  claim 1 , wherein the Ti 1−x Al x C y N z  layer has stoichiometry coefficients 0.70≤x<1,y=0 and 0.95≤z<1.15. 
     
     
       9. A tool according to  claim 7 , wherein the preferential orientation of the crystal growth of the Ti 1−x Al x C y N z  layer is present with respect to the crystallographic {111}-plane. 
     
     
       10. A tool according to  claim 1 , wherein the Ti 1−x Al x C y N z  layer has a preferential orientation of crystal growth with respect to a crystallographic {hkl}-plane, which is characterised in that the maximum of the X-ray diffraction peak of the crystallographic {hkl}-plane, measured by X-ray diffraction diffractometry (XRD) and/or by electron backscatter diffraction (EBSD), is measured within an angle a α=±20degrees relative to the perpendicular to the surface of the base body,
 wherein the preferential orientation of the crystal growth of the Ti 1−x Al x C y N z  layer is present with respect to the crystallographic {111}-, {200}-, {220}- or {311}-plane. 
 
     
     
       11. A tool according to  claim 10 , wherein the maximum of the X-ray diffraction peak of the crystallographic {hkl}-plane, measured by X-ray diffraction diffractometry (XRD) and/or by electron backscatter diffraction (EBSD), is measured within an angle α=+10 degrees relative to the perpendicular to the surface of the base body. 
     
     
       12. A tool according to  claim 10 , wherein the preferential orientation of the crystal growth of the Ti 1−x Al x C y N z  layer is present with respect to the crystallographic {111}-plane. 
     
     
       13. A tool according to  claim 1 , wherein the full width at half maximum (FWHM) of at least one of the X-ray diffraction peaks of the crystallographic {111}-, {200}-, {220}- and {311}-planes is <1° 2θ. 
     
     
       14. A tool according to  claim 13 , wherein the full width at half maximum (FWHM) of at least one of the X-ray diffraction peaks of the crystallographic {111}-, {200}-, {220}- and {311}-planes is <0.6° 2θ. 
     
     
       15. A tool according to  claim 13 , wherein the full width at half maximum (FWHM) of the X-ray diffraction peaks of the crystallographic {111}-plane is <1° 2θ. 
     
     
       16. A tool according to  claim 1 , wherein the Ti 1−x Al x C y N z  layer has a preferential orientation of crystal growth with respect to the crystallographic {111}-plane, which is characterised by a ratio of the intensities of the X-ray diffraction peaks of the crystallographic {111}-plane and the {200}-plane, l{111} and l{200}, in which l{111}/l{200} >1+h(In h) 2 , wherein h is the thickness of Ti 1−x Al x C y N z  layer in “μm”. 
     
     
       17. A tool according to  claim 16 , wherein l{111}/l{200} >1+(h+3)×(ln h) 2 . 
     
     
       18. A tool according to  claim 7 , wherein the texture coefficient TC (hkl) is greater than 2. 
     
     
       19. A tool according to  claim 1 , wherein the Ti 1−x Al x C y N z  layer has a Vickers hardness (HV)>2300 HV. 
     
     
       20. A tool according to  claim 1 , further comprising, arranged between the base body and the Ti 1−x Al x C y N z  layer, at least one further carbide layer of a thickness of 0.05 μm to 7 μm, selected from a TiN layer, a TiCN layer deposited by means of high temperature CVD (CVD) or medium temperature CVD (MT-CVD), an A 1   2 O 3  layer and combinations thereof and/or arranged over the Ti 1−x Al x C y N z  layer is at least one further carbide layer. 
     
     
       21. A process for the production of a tool according to  claim 1 , wherein, for producing the Ti 1−x Al x C y N z  layer with a lamellar structure, the process comprises:
 a) placing the body to be coated in a substantially cylindrical CVD reactor designed for an afflux flow of the bodies to be coated with the process gases in a direction substantially radially relative to the longitudinal axis of the reactor, 
 b) providing two precursor gas mixtures (VG1) and (VG2), wherein the first precursor gas mixture (VG1) contains 0.005% to 0.2 vol-% TiCl 4 , 0.025% to 0.5vol-% AlCl 3  and as a carrier gas hydrogen (H 2 ) or a mixture of hydrogen and nitrogen (H 2 /N 2 ) and the second precursor gas mixture (VG2) contains 0.1 to 3.0vol-% of at least one N-donor selected from ammonia (NH 3 ) and hydrazine (N 2 H 4 ) and as a carrier gas hydrogen (H 2 ) or a mixture of hydrogen and nitrogen (H 2 /N 2 ) and the first precursor gas mixture (VG1) and/or the second precursor gas mixture (VG2) optionally contains a C-donor selected from acetonitrile (CH 3 CN), ethane (C 2 H 6 ), ethene (C 2 H 4 ) and ethyne (C 2 H 2 ) and mixtures thereof, wherein the total vol-% proportion of N-donor and C-donor in the precursor gas mixtures (VG1VG2) is in the range of 0.1 to 3.0vol-%, 
 c) maintaining the two precursor gas mixtures (VG1, VG2) separate before passing into the reaction zone and introducing the two precursor gas mixtures (VG1, VG2) substantially radially relative to the longitudinal axis of the reactor at a process temperature in the CVD reactor in the range of 600° C. to 850° C. and a process pressure in the CVD reactor in the range of 0.05 to 18kPa, 
 wherein the volume gas flows ({dot over (V)}) of the precursor gas mixtures (VG1, VG2) are so selected that the mean residence time (T) in the CVD reactor is less than 1 second. 
 
     
     
       22. A process according to  claim 21 , wherein the volume gas flows ({dot over (V)}) of the precursor gas mixtures (VG1, VG2) are so selected that the mean residence time (T) in the CVD reactor is less than 0.5 second. 
     
     
       23. A process according to  claim 21 , wherein at least one of the process temperature in the CVD reactor is in the range of 625° C. to 800° C. and the process pressure in the CVD reactor is in the range of 0.05 to 8kPa. 
     
     
       24. A process according to  claim 21 , wherein the ratio of the volume gas flows ({dot over (V)}) of the precursor gas mixtures (VG1, VG2) ({dot over (V)}(VG1)/{dot over (V)}(VG2)) is less than 1.5. 
     
     
       25. A tool according to  claim 1 , further comprising, arranged between the base body and the Ti 1−x Al x C y N z  layer, at least one further carbide layer of a thickness of 0.05 μm to 7 μm, selected from a TiN layer, a TiCN layer deposited by means of high temperature CVD (CVD) or medium temperature CVD (MT-CVD), an Al 2 O 3  layer and combinations thereof and/or arranged over the Ti 1−x Al x C y N z  layer is at least one Al 2 O 3  layer of the modification γ-Al 2 O 3 , κ-Al 2 O 3  or α-Al 2 O 3 . 
     
     
       26. A tool according to  claim 1 , further comprising, arranged between the base body and the Ti 1−x Al x C y N z  layer, at least one further carbide layer of a thickness of 0.05 μm to 7 μm, selected from a TiN layer, a TiCN layer deposited by means of high temperature CVD (CVD) or medium temperature CVD (MT-CVD), an Al 2 O 3  layer and combinations thereof and/or arranged over the Ti 1−x Al x C y N z  layer is an α-Al 2 O 3  layer, wherein the Al 2 O 3  layer is deposited by means of high temperature CVD (CVD) or medium temperature CVD (MT-CVD).